Article by Capt. Steve Katz
Night Moves
Boating in the dark is often a necessity, usually on the way to or from a fishing spot, an unexpected delay or on an extended voyage. Traditionally using your GPS chartplotter and or radar is a great way to know where you are and what is around you. Radar does a great job of displaying large objects like boats and land that reflect a radar signal. A GPS chartplotter can show you where your boat is in relation to an electronic chart, helping you navigate to your destination.
There are a few different type of tools that are available to boaters that can help with nighttime operations:
Radar is one of the only technologies that let us “see” over the horizon. Modern doppler radars improve on the effectiveness of a traditional radar when it comes to navigational safety. A doppler style radar, also referred to as solid state are offered by the major marine electronic companies, such as: Furuno NXT, Garmin Fantom, Simrad Halo and Raymarine Quantum. These style radars use the Doppler effect to calculate a radar targets movement in relation to your boat’s movement. If the radar determines the other object is stationary, like a buoy, jetty, pier etc., then the radar displays the target as a traditional return. If the radar determines the object is moving in a direction that could put it on a collision path with your vessel, the radar usually differentiates this radar return with a different color, often red. If the radar determines that an object is moving away from your boats path of travel and is not currently a collision danger, the radar return is colored green. Each brand of doppler radar may work slightly differently but the basics are the same – the radar preforms these doppler calculations on all returns and gives you a much better idea of the moving and stationary objects picked up by the radar. This technology can give even the most novice radar operator the confident ability to understand their surroundings with relative ease. Remember, your radar works just as well in the day as the night – you should use it whenever you need to improve your situational awareness.
The LED light bar is a trending must-have for many boaters operating in the dark. Often used like the headlights on a vehicle, a mounted light bar can provide a large amount of light covering a wide area in front of the boat, illuminating your path forward. This is helpful when entering and exiting a confined or unfamiliar area, such as a marina, inlet, channel or other are where visual navigation is critical. These modern light bars produce a lot of light with a little bit of power, with many size offerings for most any size boat.
One drawback is that the light can be too bright when other boaters are nearby and disturbing the vision of other captains, diligent use is needed when near other boaters. Another issue that could arise is that USCG Rule 20 specifies that only those navigation lights prescribed, or those that don’t interfere with those prescribed, may be used while underway.
Once darkness falls, the ability to see through the dark is comforting and adds a layer of safety. There technologies to help us see through in the dark, without bright lights or interoperating a radar picture.
The traditional “night vision” is one of the tools available to mariners, though not as popular as it once was with boaters. This night vision is the fuzzy green pictures you may have seen from military or police videos. First used in WWII, this consists of a camera sensor that intensifies the existing light (however little exists) or supplies its own near infrared light, to render the greenish image of what is front of the lens. The green image was chosen by manufacturers because our eyes are most sensitive to green light, and it shows the most accurate user-friendly picture for humans to see. This technology can sometimes offer more detail because it responds to light more like the eye does. These night vision systems have come down in cost and may be a great addition to your on-board gear. Since this night vision requires reflected light, they do not work well at long range, or when it is very dark, rainy, or foggy. It is a good tool to read numbers on a buoy, see a wake in the water or other features in detail, similar to how you would see in the daytime.
These devices come in many physical forms, the handheld binocular or monocular is the most popular and affordable for marine use.
A low light camera is similar to a conventional mounted video camera, sends a feed to a dedicated monitor or MFD (multifunction display) on the helm. A low light camera has a special CMOS sensor that can produce a video image that uses the ambient nighttime light and processes the video image that looks similar to what you might see in the daytime on a video camera. The quality of the picture relies on the amount of ambient light and the technology of the camera.
The most sophisticated type of “night vision” is thermal imaging or thermal camera (often called FLIR, an acronym for Forward Looking Infra Red ). Thermal night-vision cameras rely on technology that senses extremely small temperature differences — not reflected visible light. Consumer FLIR cameras uses a crystal lens to capture temperature information and focus it onto a vanadium oxide microbolometer, this device converts the temperature measurement into electrical signals that are processed to produce the visible video image. Because ambient light is not used at all by a thermal camera, the system can produce the same type of picture during the daytime as it does at night. The FLIR device can help you spot objects that may be hard to see even during daylight hours. FLIR devices were original developed for and used in the military, police, and firefighting markets and due to the high costs not many consumer products were available in the past. Now many of these FLIR devices have become more affordable for boating use, with fixed mount consumer marine devices starting at $3749 and handheld about $2000.
Accident avoidance is an area where a thermal camera can help you see objects floating in the water, since they often have a different temperature than the surround water and therefore be differentiated on the video output. Other objects such as boats, land masses, buoys and people are easily identified by their temperature differences. If you are using this system for search and rescue, looking at cool water for a warm person, they will be easy to spot due to the contrast of temperature. No other visual technology finds people in the water faster.
The type and resolution of the thermal camera and the video screen used to display the image from a camera can make a significant difference in picture quality, be sure to compare choices before making a purchase. Thermal cameras usually work in light rain or light fog, but heavier precipitation can appear as a “wall” of same temperature, decreasing the usefulness of the camera during severe weather. These systems can be good for long distance viewing but are not often helpful in reading numbers on a buoy, because the camera reads the temperature, so if the buoy numbers are the same temperature as the buoy, the system does not differentiate this, and the buoy appears without numbers.
The most popular marine thermal cameras are made by FLIR Systems and OmniSense. Hand-held thermal cameras begin around $2000, and a fixed mount MD series begin around $3500. Both the FLIR and OmniSense can integrate with today modern chart plotters, in addition to seeing the thermal picture on the screen, many chart plotter displays allow you to use the touchscreen to control the camera movements and settings.
An interesting feature on some of these chart plotters is “Slew-to-Cue” a feature that allows the chartplotter to control and keep the camera pointed to and track a specific object, such as a moving boat.
All the above technologies are a good tool for nighttime navigation, shipboard security, man overboard situations, anti-piracy, and many other applications. These devices are also ideal for navigation, showing channel markers, shipping lane traffic, outcroppings of land, bridge pilings, debris, exposed rocks, other vessels and indeed any other hazardous floating object.
Until next time...
Stay Grounded
